Content providers use audience measurement systems to estimate the size of an audience that watches a media content instance such as a particular television show or movie. These audience measurement systems sample the viewing habits of a subset of a population to estimate the number of people or households in the population that viewed a particular media content instance. This information is important to advertisers who are generally willing to pay more to advertise during media content instances that have larger audiences. In addition, this information may be published so that consumers know which media content instances are popular among the population.